My hard drive failed, put in new hard drive, reinstalled windows XP pro, everything was working fine. Restart, or turn off computer and booted to windows. I went to the bios to check to make sure num lock was on, didn't change anything in the bios, exited the bios and now get this error message of missing operating system.

So, I erased the hd and did everything again! IT was fine until I just looked into the bios without changes. I can boot to the HD by interrupting with enter and F12. It can't be the new hard drive, it was working until I looked at bios (no changes made) and able to go to hard drive and it boots. What is happening!

What is happening when you hit ENTER & F12?

Is this a legit copy of Windows?

Found out that the solution was simple, don't have USB drive plugged in! Happy New Year to all... thanks for help in 2010.

Thanks for the update. If you're BIOS is set to boot from USB before HDD then yes I can see your error happening. Hmmm..

Happy New Years to you as well!

Yes legit copy, F12 works, just was starting computer with thumb drive in USB port. Take it out, and everything is fine. Thanks for help.

No problem!